The instrument requested in this application is a Seahorse Extracellular Flux Analyzer package consisting of 6 well and 96 well platforms suitable for pilot studies and larger high throughput studies, respectively. These instruments are manufactured by Seahorse Bioscience. The purchase price includes on-site training and a one-year warranty. Data analysis software is available from the manufacturer for no charge and may be installed on an unlimited number of workstations. The instrument measures cellular respiration through changes over time on oxygen concentration and pH and is able to discern the portion of cellular respiration attributable to mitochondria or glycolysis. In addition, pharmacological manipulations permit one to measure mitochondrial and glycolytic reserve capacity and baseline cellular respiration. Using additional reagents, one can measure the fraction of cellular respiration attributable to metabolism of carbohydrates and fats. These measurements are obtained using two, separate sensors that are immersed in cell culture fluid and pre-mixed reagents purchased from the manufacturer. The instrument is designed to be easily used by individuals who do not have specialized training in metabolomics and is the de-facto standard for measuring metabolic parameters in living cells. Measurements may be obtained from cultured cell lines, primary cultures or tissue sections. Specialized, disposable plastic plates must be used for the measurements. Cells or tissues are placed into wells on these plates and can be maintained in cell culture incubators similarly to routine cell culture systems. No equivalent instrument is available at JJPVA. Use of the closest Seahorse platform, located at our academic affiliate the Icahn School of Medicine at Mount Sinai, is not feasible because of the challenges of transporting cell cultures over the 10 miles that separate the institutions. If funded, this application would afford JJPVA investigators access to the gold standard for cell metabolomics measurements. The instrument will be used in VA-funded projects in the fields of Alzheimer's disease, traumatic brain injury, HIV pathogenesis, and spinal cord injury. The instrument would add the capacity for systematic study of cellular metabolism in cells and cultured cells and, thereby, substantially broaden and enhance the understanding of medical conditions that affect the health and quality of life of veterans impacted by these diseases and disabilities.